background
x
loader
Troubleshooting
arrow By ATA By Message Color By Observed Faults by MDCBy Tips

Select color for CAS message that you wish to troubleshoot

(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

This page includes :

For AOG assistance contact:

CRC Montreal (YUL)
Quick Links

06/08/22

Message Overview:

Message Name:

SELECT VALVE STUCK OPEN

Message Code:

B3-007266

Associated CAS:

NWS FAULT
(Advisory)

Reporting LRU: NWS SELECT VALVE
System Description: 32-51-00
Schematic Diagram: 32-51-00
Wiring Diagram: 32-51-01

Message Description:

Nosewheel Steering Selector Valve is stuck Open and indicates that hydraulic pressure is sensed in the Steering System while the Steering Selector Valve (SSV) is commanded shut.

Possible Causes:

  • Steering Selector Valve (SSV) (V7)
  • Steering Pressure Switch (S10)
  • Steering Control Unit (SCU) (A73)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

  • AW300-32-0396 - Nose Landing Gear (NLG) - Nose Wheel Steering Slow to Deactivate

Forum Articles/Infoservice/Newsletter: None

NOTE: Review the AW300-32-0396 if the NWS is slow to deactivate. The action for an AD associated with the Nose Wheel Steering Selector Valve is described in AW300-32-0396. 
NOTE: Review the "NOSEWHEEL STEERING" System Description Section.
NOTE: Switching the NWS PBA to "OFF" or removing power from the aircraft will clear the cyan "NWS FAULT" advisory CAS message. If the fault is still present, it will not be shown again until the next Weight-Off-Wheel condition with hydraulic pressurized and NWS PBA set to "ON".
NOTE: The SCU memory does not record this fault and the 7-segment display will indicate "0", no fault.
NOTE: The pressure switch (S10) contacts open at 1400 psi and close at 1800 psi.
NOTE: In the case where the cyan "NWS FAULT" or B3-007266 is not associated with a code "2" on the SCU 7-segment display, then it is most likely a pressure switch problem.

Quick Links:

Pressurize the Left and Right Hydraulic Systems AMM 29-10-00-862-801
Release Hydraulic Pressure - Left and Right Hydraulic Systems AMM 29-10-00-862-802
Operational Test of the Nosewheel-Steering Control System AMM 32-51-00-710-801
Rigging of the Nosewheel-Steering Control System (Preferred Method) AMM 32-51-00-820-801
Rigging of the Nosewheel-Steering Control System (Alternate Method) AMM 32-51-00-820-803
Removal of the Steering Control Unit AMM 32-51-01-000-801
Installation of the Steering Control Unit AMM 32-51-01-400-801
Removal of the Steering Selector Valve AMM 32-51-09-000-801
Installation of the Steering Selector Valve AMM 32-51-09-400-801
Operational Test of the Steering Selector Valve AMM 32-51-09-710-801
Removal of the Steering Pressure Switch AMM 32-51-25-000-801
Installation of the Steering Pressure Switch AMM 32-51-25-400-801
Put the Aircraft in a Weight-Off-Wheel Configuration with the Aircraft on the Ground AMM 32-61-00-867-801
Remove the Aircraft from a Weight-Off-Wheel Configuration with the Aircraft on the Ground AMM 32-61-00-867-802
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Electrical Wiring - Continuity Test - Adjustment /Test - ALL SPM 20-12-01-05
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02

Troubleshooting Recommendations:

NOTE: If work was previously carried out on the left hydraulic system prior to this issue, check the left hydraulic system manifold return filter for condition and especially debris.

  1. Make sure left hydraulic system is depressurized (AMM TASK 29-10-00-862-802).
  2. Make sure NWS PBA is selected 'OFF' (OFF legend is lighted).
  3. Measure resistance at the Pressure Switch (S10) receptacle per the following table:

    FROM TO EXPECTED RESULTS ACTUAL RESULTS
    A B OPEN (∞Ω)
    B CASING OPEN (∞Ω)

    1. If there is continuity, replace Pressure Switch S10.
    2. If no fault found, go to the next step.

  4. Measure resistance at the Pressure Switch harness connector (S10P1) per the following table:

    FROM TO EXPECTED RESULTS ACTUAL RESULTS
    B GND OPEN (∞Ω)

    1. If there is continuity, repair wiring as required.
    2. If there is no continuity, go to the next step.
      NOTE: Always establish Left Hydraulic System pressure before switching the NWS System to 'ON' as it may trigger and record a false 'NWS FAIL' message if any NWSS component is out of neutral position.

  5. Pressurize left hydraulic system (AMM TASK 29-10-00-862-801).
  6. Set the NWS PBA to ON (OFF legend is extinguished).
  7. Put the Aircraft in a Weight-Off-Wheel configuration with the aircraft on the ground (AMM TASK 32-61-00-867-801) using the MDC Override Mode Discrete Output.

    1. If the cyan 'NWS FAULT' EICAS message is displayed, replace SSV.
    2. If not, the SSV is no longer stuck open.
      NOTE: It is recommended to carry out the Operational Test of the Nosewheel-Steering System (AMM TASK 32-51-00-710-801), doing 10 full-swings of the steering system to flush out any particle that may have jammed the SSV.

  8. Release the Hydraulic System Pressure (AMM TASK 29-10-00-862-802).
  9. Do close out.

Registered and/or unregistered trademarks of Bombardier Inc. or its subsidiaries. © 2015 Bombardier Inc. All rights reserved.